<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>htmlcss 阶段</title>
    <style>
        .container {
            width: 1000px;
            height: 300px;
            background-color: #ccc;
            overflow: hidden;
            margin: 0 auto;
            display: flex;
            align-items: center;
        }
        .container > div {
            border-radius: 50%;
            border: 1px solid #fff;     
            background-color: rgba(255,0,0,1);
            flex-shrink: 0;
            box-sizing: border-box;
        }
    </style>
</head>
<body>
    <div class="container">
        <!-- <div style="width:40px;height:40px; opacity: 1;"></div> -->
    </div>


<script>
    // 要求：
        // 编写函数 createCircle ，创建标签并添加到.container标签内
        // 创建的标签，尺寸（w,h）初始化值为 40, 透明度(a)为1
        // 然后每调用一次函数后，创建的标签的尺寸自增10px ,透明度减去 0.08

        var createCircle = function () {
            var width = 40 ; 
            var height = 40 ;
            var opacity = 1 ;
            var div = document.createElement("div");
            div.style["width"] = width + "px";
            div.style["height"] = height + "px";
            div.style["opacity"] = opacity + "px";
        }
</script>
</body>
</html>